1. Field of the Invention
The present invention relates in general to passive seat belt arrangements for use in a motor vehicle, and more particularly to passive seat belt arrangements of a type wherein one end of the seat belt is connected to a carrier which is slidable along a guide rail attached to a roof side panel and its neighbouring panel of the vehicle.
2. Description of the Prior Art
One of conventional passive seat belt arrangements of the above-mentioned type is disclosed in Japanese Utility Model Second Provisional Publication No. 58-14131, which, as is shown in FIG. 3 of the attached drawings, comprises a belt retractor 3 mounted to an inboard side of a seat 1 for retracting or feeding a webbing 2. A curved guide rail 7 extends along a front pillar 4, a roof side rail 5 and a center pillar 6 of the associated vehicle. The guide rail 7 is obtusely curved at the jointed portion between the front pillar 4 and the roof side rail 5, but largely curved at the jointed portion between the roof side rail 5 and the center pillar 6. The largely curved portion of the guide rail 7 is denoted by numeral 7a in the drawing. A carrier 8 to which one end of the webbing 2 is fixed is slidably guided by the guide rail 7. To a rear end portion of the guide rail 7, there is mounted an anchor device 9 which functions to latch the carrier 8 when the latter is moved thereto to restrain a seat occupant (not shown) with the webbing 2.
The detailed construction of the largely curved portion 7a of the guide rail 7 and that of the carrier 8 are shown in FIG. 4. As is seen from this drawing, the carrier 8 comprises an apertured arm portion 10 to which the end of the webbing 2 is fixed and a base portion 11 which is slidably received in a guide groove (no numeral) of the guide rail 7. The base portion 11 is provided with rollers (no numerals) for smoothing the movement of the carrier 8 along the guide rail 7. The carrier 8 is formed between the arm portion 10 and the base portion 11 thereof with an elongate recess 12. As will be understood from a lower half of the drawing (FIG. 4), when the carrier 8 comes to the anchor device 9, the recess 12 receives therein a stop pin 9a of the anchor device 9, so that the pin 9a can tightly hold the carrier 8 against the force which is applied to the carrier 8 from the webbing 2 in the direction of the arrow F. As is seen from FIG. 3, a flexible wire 14 is connected to the carrier 8, which is driven by an electric motor (not shown) mounted in the vehicle. Known sensors and control devices are connected to the electric motor, so that when a side door 13 assumes its closed position with the seat 1 unoccupied, the carrier 8 assumes its foremost position in the guide rail 7 as shown in FIG. 3, while when the side door 13 is closed with the seat 1 occupied by a passenger, the carrier 8 is moved rearward and downward along the guide rail 7 to the anchor device 9 and latched by the stop pin 9a of the anchor device 9, as is seen from the lower half of FIG. 4. With this operation, the webbing 2 is automatically applied to the passenger when he sits on the seat 1 and closes the door 13.
However, the above-mentioned passive seat belt arrangement has a following drawback due to its inherency in construction. That is, as is seen from an upper half of FIG. 4, when the carrier 8 takes a position other than the vertically extending part of the guide rail 7 (viz., other than the position on the center pillar 6), the arm portion 10 of the carrier 8 is directed backward. That is, when the carrier 8 passes through the largely curved portion 7a of the guide rail 7, the arm portion 10 of the carrier 8 changes its posture, viz., its pointing direction from forward to backward or vice versa. However, this posture change of the carrier 8 brings about a very dangerous matter in that when the carrier 8 is moved backward along the horizontal part of the guide rail 7 toward the largely curved portion 7a of the same, the recess 12 of the carrier 8 is finally closed by a curved inner edge 15 of an upper portion of the center pillar 6 reducing the size of an enclosed space 16 therebetween gradually. The provision of such enclosed space 16 is very dangerous because it tends to injure fingers of a passenger in the vehicle. Although this drawback may be avoided by displacing the guide rail 7 to an upper position indicated by the phantom lines in FIG. 4, a vehicle equipped with a sun-roof can not accept such displacement because the upper portion of the roof side rail of such vehicle is largely occupied by parts of the sun-roof.